UROMYCES. 



335 



epidermis are reduced in number ; intercellular spaces are formed 

 in the normally compact palisade parenchyma, and its cells 

 become shorter and broader, while those of the spongy paren- 

 chyma are increased both in size and number ; the fibro-vascular 

 bundles remain unchanged, although the cells surrounding them 

 may be more or less abnormal. Where thickening of the stem 

 takes place, it is chiefly due to multiplication of the cells of 



Fig. ISO. — Vvomycei pisi. Comparison of healthy flowering plant of Euphorbia 

 Cyparissias, with a much-elongated, non-flowering plant bearing aecidla of Pea- 

 rust, (v. Tubeuf phot.) 



cortex and pith, while at the same time those of the cortical 

 parenchyma become somewhat enlarged and altered in shape ; 

 the woody portion is less developed than normally ; and 

 laticiferous tubes are neither so large nor so conspicuous as 

 usual. 



The aecidia of this species are found only on the lower 

 surface of the leaf; they are saucer-shaped, and have a broad 

 lobed white margin. 



